Electrical condenser



Aug. 19, 1941.

F. w. GODSEY. JR

ELECTRICAL CONDENSER Filed Sept. 26, 1940 FRANK W GOD-55K JR INVENTOR. BY M M #fian ATTORNEYS.

Patented Aug. 19, 1941 2.25am annc'rmoan oonn'ansaa Frank W. Godsey, In, North A dams, signer to Sprag'ue Specialties 00., North Adams, 7 Man, a corporation of Massachusetts Application September 26, 1940, Serial No. 358,548

6 Claims.

The present invention relates to electrical condensers, and more particularly to novel improvements in condensersof fixed capacity value.

It is an object of the invention to provide a fixed capacity condenser characterized by a high degree of mechanical and electricalstability.

A further object is to provide a fixed capacity condenser which is small and compact, exhibits a high capacity value and which can be manufactured at a low cost.

In the manufacture of fixed-capacity condensers, variations in the effective area of the electrodes, in the thickness of the dielectric layers, etc., may cause large differences between the individual capacities of supposedly identical condensers. On the other hand, in many uses of these condensers, it is imperative that the capacity of the condenser is accurate within narrow tolerances.

It is therefore another object of the invention to provide a fixed capacity condenser which in manufacture is simply and inexpensively adjusted within narrow tolerances to a predetermined capacity value.

These and further objects of the invention will appear as the specification progresses.

The invention consists in novel methods of construction and arrangement of parts, which will be described in the specification and set forth in the appended claims.

More particularly, the invention relates to an improved fixed-capacity condenser comprising as its main elements, two circumjacent electrodes and an interposed dielectric layer which is intimately united with the electrodes.

In the drawing forming part of the specification:

Figure 1 is a side view in cross-section of a condenser made in accordance with the invention. 5

Fig, 2 is a side view in cross-section illustrating another embodiment of the invention.

Referring to Fig. 1, the condenser there shown comprises two concentrically disposed electrodes l0 and II and a dielectric layer l2 interposed between the electrodes.

Electrode l0 consists of a metal cylinder at the two end faces l3 and ll of which there are provided shallow axial bores l5 and "respectively. The bore I5 is of such diameter as to snugly preferably countersunk at its open end as shown at 20, within which the lead is welded at it.

The bore I I has an interconical and an inner cylindrical part adapted to receive a flexible terminal wire II as later to be more fully described.

The dielectric I2 consists of a layer of an insulating material forming an integral coating on the surface of the cylinder l0, said coating also extending over the end faces It and H of the cylinder, whereby at the end face i3 it preferably covers the weld portion I! but permits the terminal lead I 'l to project through it, and at the end face I! it forms a lining 2| of the bore II.

The layer l2 consists preferably of a fused potassium lead silicate vitreous enamel as disclosed in the copending application of Stanley 0. Dorst, Ser. No. 289,292, filed August 9, 1939. The layer l2 may consist of other suitable dielectric materials, for example, of other vitreous dielectric enamels or of other refractory dielectric materials capable of being applied to the surface of electrode Ill and of forming an integral coating on the surface thereof. Preferably the layer I2 is applied to the electrode ill by cataphoretic deposition, as described in the copending application of Preston Robinson et al., Ser. No. 197,692, filed March 23, 1938, which process provides for a coating of uniform thickness throughout its area; the lining 2| being thereby also of uniform thickness and free of weak spots or other surface imperfections.

The outer electrode consists of a conducting metal coating ll provided on the surface of the dielectric l 2 and extends over the dielectric coating towards the end face I! and also covers the end face It, forming thereby a covering lining 22 over lining II, and within which the terminal wire it is secured for example, by soldering, as shown at 23.

The coating ll may be formed in one of several manners. For example, it may be applied by spraying finely divided copper on the dielectric layer l2, forming an adhering and homogeneous layer thereon. Preferably, the coating ll consists of a thin layer or film of silver which is applied to the surface of the dielectric I! by chemical deposition from a suitable silvering solution or by the decomposition of an organic silver salt painted or sprayed as a layer on the surface of the dielectric.

The condenser of the invention readily lends itself to the adjustment of its capacity value within close capacity tolerances. Such close tolerances are simply and inexpensively obtained the electrode II, for example, by means of a grinding machine. Preferably, the grinding machine is provided with electrically insulated inandrels for holding the condenser during the grinding of the electrode ii. To such mandrels there may be connected a suitable capacity measuring device controlling the action of the grinding machine whereby the grinding is automatically stopped when the condenser is brought to the desired capacity value.

It is thus seen that the invention provides a fixed capacity condenser of great rigidity and mechanical strength, and which is compact. contains a minimum number of components and is readily adapted to low cost and mass production.

Moreover, since the components of the condenser are integrally united, their active surfaces are hermetically sealed from all external influences such as humidity and the like and the condenser exhibits a high degree of stability when subjected to such influences.

In Fig. 2 there is shown the novel construction of the invention as applied to a fixed capacity condenser of low capacity value and/or of high breakdown voltage.

The condenser of Fig. 2 comprises a metal cylinder 30 at the two end faces 3! and 32 of which there are provided shallow axial bores 33 and 34 respectively. Each of the bores 33 and 34 are preferably countersunk for example, as shown at 33 and 33 respectively.

Disposed on the surface of cylinder 30 is an integral coating 31 of a vitreous dielectric material which coating extends over the end faces 3| and 32 of the cylinder 30 and forms within the bores 33 and 34 linings 38 and 39 respectively.

The electrodes of the condenser consist of conducting metal coatings 40 and 4| provided on the surface of the layer 31 and each extending towards end faces of the cylinder 30 and into the corresponding coated bores 33 and 34 forming therein linings 41 and 48 respectively. The electrodes 40 and 4i are formed in the manner previously described in connection with the electrode i I of the condenser of Fig. 1.

External electrical connection to the electrodes 43 and 4| is provided by flexible wire leads 42 and 43 respectively, said leads being secured within the lined bores 33 and 34 respectively, and connected to the electrodes by soldering, for example, as shown at 44 and 45 respectively.

The invention has been described in connection with condensers in which the electrodes are cylindrical in cross-section. It should be well understood, however, that the principles of the invention are equally applicable to condensers with electrodes of other cross-sectional shapes, for example, of oval or rectangular cross-section.

While I have described my invention by means of specific examples and in specific embodiments, I do not wish to be limited thereto for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

What I claim is:

1. An electrical condenser comprising a metal core having an end face, a bore in said end face, a dielectric layer forming an integral coating on by removing selected portions of the surface of the surface of said core and extending over said end face and forming a lining within said bore, a condenser electrode comprising a metal coating integrally disposed on the surface of said dielectric layer and circumjacent to said core, and terminal means for said. electrode comprising a member disposed in said lined bore and secured to the surface of said electrode.

2. An electrical condenser comprising a center electrode having two end faces, a bore in each of said end faces, a dielectric layer forming an integral coating on the surface of said electrode and extending over one end face and forming a lining in the bore thereof, a second electrode comprising a metal coating integrally disposed on the surface of the dielectric layer, terminal means for said condenser, said means comprising a wire element disposed in the lined bore and secured to the metal coating and a second wire element secured within the center electrode.

3. An electrical condenser comprising a metal core having two end faces, a bore in each of said end vfaces, a dielectric layer integrally disposed on the surface of said core and extending over said end faces and forming a lining within said bores, two metal coatings integrally disposed on the surface of said dielectric layer and extending over the opposing end faces of said core, terminal means for said condenser, said means comprising wire elements disposed in said lined bores and secured to said metal coatings.

4. An electrical condenser comprising a metal cylinder having two end faces, an axial bore in one of said end faces, a dielectric layer forming a fused integral coating on the surface of said cylinder and extending into said bore and forming a lining therein, a condenser electrode comprising a metal coating integrally disposed on the surface of said dielectric layer, and terminal means for said electrode comprising a wire element disposed in said lined bore and secured to said coating.

5. An electrical condenser comprising a cylindrical electrode having two end faces, an axial bore in each of said end faces, a dielectric layer forming an integral fused coating on the surface of said electrode and extending over one of said end faces and forming a lining in the bore thereof, a second electrode comprising a concentric metal coating integrally disposed on the surface of the dielectric layer, terminal means for said condenser, said means comprising a wire element disposed in the lined bore and secured to the metal coating and a second wire element secured within the other bore of said cylindrical electrode.

6. An electrical condenser comprising a metal cylinder having two end faces, an axial bore in each of said end faces, a dielectric layer integrally disposed on the surface of said cylinder and extending over said end faces and forming a lining within each of said bores. two metal coatings integrally disposed on the surface of said dielectric layer and extending over the opposlng end faces of said cylinder, terminal means for said condenser, said means comprising wire elements dsposed in said lined bores and secured to said metal coatings.

FRANK W. GODSEY, JR. 

